Placed overworld blocks in the nether will BLOCK mob spawning

Now that the netherworld has become a live-able area, I find it absurd that I need to place buttons on every block inside my outpost.  

• Any block that is not native to the nether will prevent all creature spawns on that block.
• Nether mobs will never spawn around a torch.
• A ghast will never spawn in the air if there is an overworld block less than 8 blocks above or beneath it.  (prevents ghasts from spawning inside your house)